best audio quality: 192 2.0 or 384 5.1 dd?

[plonk]

what's the best for conversion to stereo 2.0 sound:

192kbs Dolby 2.0 or
384kbs DD 5.1?

i know at least part of the time, the 2.0 channel is a special mix for 2.0 systems, but 192kbs seems a little .. low. is the sound on 5.1 mixes any better?

[kinneera]

Do a proper downmix with a tool like Azid and the 5.1 should be the better source.

[wildcatfan]

uhm...no.....use the 2.0 if doing svcd/vcd. It *should* be downmixed already by the studio...who of course have much better equipment than we have. Also think about it.....192 2ch = 96kbps/channel.....384 5.1 = ~64/channel.....

[kinneera]

Uhm..no...5.1 bitrate allocation isn't that simple, especially given that the LFE channel isn't really a full channel. But even then, a proper downmix will intelligently merge information from all of the channels into the two-channel stereo form, thus you get roughly 192Kbps per channel, which in a sense means you actually have more data than you need for 224Kbps stereo rather than less.

[vitualis]

I would have to agree with wildcatfan on this one.

The 2.0 soundtrack would have already been downmixed from the 5.1 audio to Dolby Surround encoded audio by the studio and they would probably do it better than any non-Dolby authorised tool. Since you are aiming for a Dolby Surround encoded stereo file anyway, the 2.0 soundtrack is probably a better choice.

Regards.

[kinneera]

When doing what really amounts to double compression encoding (ac3->mp2), I would rather take my chances with a "non Dolby-authorised tool" and have more actual bits to work with, but I guess it's a matter of personal choice.

[Kdiddy]

Ok but lets deal in reality on this particular issue....as Kinneera stated, a properly done downmix of the 5.1 channel is very much equal to the 2.0 downmix by the studio. And to my ears, on a very good soud system, I can not decipher the difference between the 2 (with 5.1 version via BeSweet/Azid/Lame).

[wildcatfan]

Ok but lets deal in reality on this particular issue....as Kinneera stated, a properly done downmix of the 5.1 channel is very much equal to the 2.0 downmix by the studio. And to my ears, on a very good soud system, I can not decipher the difference between the 2 (with 5.1 version via BeSweet/Azid/Lame).

Actually....I don't think this is the case. as the studio (and director) know what sounds they want and where and sometimes change things substantially from their 5.1 mix to the 2.0 mix to get things to sound how they want them.... if not why even bother with a 2.0 mix since the dvd player would downsample it anyway if you only had dolby surround. also about the bitrate...you are not looking at much (if any difference) in bits/channel between the 2.0 and the 5.1.

[Kdiddy]

as the studio (and director) know what sounds they want and where and sometimes change things substantially from their 5.1 mix to the 2.0 mix to get things to sound how they want them

I may be wrong, but I would find it hard to believe that the director's actually put any effort into the 2.0 channel stream. Im sure they let some sound guru take that exercise on.

if not why even bother with a 2.0 mix since the dvd player would downsample it anyway if you only had dolby surround.

The reason that the 2.0 channel is included is mainly for compatibility reasons, NOT for a properly mix stream. Believe it or not, there are people out there who own receivers which do not 5.1 decoders in them. DVD players (w/o hacks) will ONLY output the 5.1 ac3 stream through the DVD players digital outputs connections, not through the regular RCA R-L outputs. Thus you need the 2.0 stream for this reason. Which is why i think some sound guru at the studio just throws the 5.1 channel into a downmixer, which would only be marginall better because he's dealing with the original source as oppose to already compressed sound like us. but I still contend that marginal difference is unnoticeable to average listener.

[wildcatfan]

well, then what are we arguing about....if the difference is marginal why bother down mixing it yourself when you have a 2.0 stream (which is what you need) sitting right on the disc???

And also I don't know of any receivers that accept digital input and don't have a decoder built in, so I don't think that is necessarily the reason.

And DVD players DO output 5.1 streams through the rca outputs....they just downmix it themselves....that was my whole point (and part of the spec I believe is that a dvd player must be able downmix to dolby surround if it a) doesn't have onboard 5.1 processor b) processor is turned off) if the dvd player does the downmixing for you why bother with a 2.0 stream unless some changes are made in the mixing process?

[Kdiddy]

well, then what are we arguing about....if the difference is marginal why bother down mixing it yourself when you have a 2.0 stream (which is what you need) sitting right on the disc???

A) No one is arguing B) I said to the average listener that the difference would be marginal, not to someone who may consider themself a sound exper. I personally do it because I can adjust certain settings to my personal preferences.

And also I don't know of any receivers that accept digital input and don't have a decoder built in, so I don't think that is necessarily the reason.

Read carefully what I wrote, I never stated anything about receivers having digital inputs with no decoders. I said receivers that dont have decoders, which usually means that if they dont have decoders, then no, they do not have digital inputs either.

And DVD players DO output 5.1 streams through the rca outputs....they just downmix it themselves

I stand corrected. Well maybe it is included because the studios/sound director doesnt trust the player/receiver to do a proper downmix of the 5.1 stream. So yes, you would be correct in saying that 2.0 is downmixed how the studio/sound director intended. I still dont think that it makes it "better" than a downmix yourself to your specs (if one knows what they are doing). It may be just me, but I still have to go through the step of doing Ac3->mp2, I just would rather work with the 5.1 stream than the 2.0.

[wildcatfan]

Hey man if you prefer it that way more power to you. I wasn't trying to convince you that you HAVE to use the 2.0 stream just that there isn't a NEED to. If you prefer the 5.1 downmixing yourself....then go for it

[plonk]

thanks for the replies..

i hear (or rather, read) that they **sometimes** put at least a little extra effort in a 2.0 studio downmix..

but i gather that the soundquality is basically the same for both 2.0 and 5.1, or undetectable enough for the unwashed masses such as myself..

thanks!

[vitualis]

i hear (or rather, read) that they **sometimes** put at least a little extra effort in a 2.0 studio downmix..

but i gather that the soundquality is basically the same for both 2.0 and 5.1, or undetectable enough for the unwashed masses such as myself..

thanks!

Exactly. The 2.0 soundtrack is not necessarily exactly equal to the 5.1 soundtrack downmixed... Depending on the studio and the amount of effort they put in, the audio may have been tweaked for the 2.0 soundtrack. Similarly, the 5.1 audio may have been tweaked so that it sounds better in 5.1 but not necessarily as good once downmixed to 2.0.

IMHO, as you are going to create a 2.0 encoded stereo file anyway, there is no reason to do an additional conversion step of downmixing 5.1 to 2.0 if the studio already provided a 2.0 downmix. There may not be a significant difference in quality, but I believe that it is reasonable to assume that the studio downmixed version (which would undoubtedly use a hardware Dolby encoder) would be either better of the same in quality. Thus, it would probably be wise to choose the 2.0 soundtrack when doing a rip when it is available.

Regards.